We have a 95 chevy cavalier -- z24 -- misfire on 1 and 3 -- we have reaplce everything avery mechanic has suggested and still no luck -- no it may be the pcm -- any suggestions?

Autozone.com provides for free, just plug in your info

most likely the ignition coil cover,the big plastic piece,they get carbon tracked and make a bad misfire,about 50 bucks

if it is a 2,4 dual over cam enginge it is the coil pack shorting out and it needs replaced

Here you go.
http://autorepair.about.com/library/firing_orders/bl-fo-10962.htm

i had the same issue with my cavalier 1998. the speed sensor wiring was chafed. fixed the wires and all is ok..hope this helps.

my friend is selling a 1997 z24 chevy calvalier manual with 148,000
miles. should i buy it for 200,dollars. its looks ok and runs ok
what should i be looking out for before i buy it.?

obviously the altenator is running to earth inside ,could be a rectifier diode .change altenator and recharge battery

try this :
with the car in park start it, then from park move it down one. if it is reverse move it down another one, now that should be neutral, then the next one should always be drive

Code P0108 is a MAP (manifold absolute pressure) sensor error.

It is either mounter directly on the intake manifold, or on the firewall.

If it is on the intake, the o-ring may have failed.

If it is on the firewall, the rubber vacuum hose may have dry rotted or just have fallen off from either the sensor, or the intake manifold vacuum fitting.

The sensors themselves very rarely fail.

Your sensor will look like one of these: